Open ERP

OpenERP is an Open Source enterprise management software. It covers and integrates most enterprise needs and processes: accounting, hr, sales, crm, purchase, stock, production, services management, project management, marketing campaign, management by affairs, ...
Once in production, it automates and help you to control all activities: sales triggers manufacturing orders, accounting entries are updated by stock operations, incoming mails are tracked in the system, the integrated document management system helps your team to collaborate, ...

Go to http://www.openerp.com/

See also these related projects.